Priority is claimed on Japanese Patent Application No. 2004-250705, filed Aug. 30, 2004, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a decentering optical system and an optical system using the same. The present invention relates to, for example, a decentering optical system which is preferable for emitting a substantially parallel beam or for focusing on a focal point surface, and an optical system using the same.
2. Description of the Related Art
In the past, there have per se been known various kinds of reflection optical systems which are decentering optical systems in which reflective surfaces are combined together so as to be mutually decentering or to slant.
For example, in FIGS. 1, 4, and 6 of Japanese Unexamined Patent Application, First Publication No. H08-313829 (hereinafter “patent document 1”), and in FIGS. 1 to 24 of Japanese Unexamined Patent Application, First Publication No. 2000-105338 (hereinafter “patent document 2”), a prism type is disclosed as this kind of reflection optical system. Furthermore, optical systems in which such optical systems are combined with light reception elements and display devices are also disclosed.
Patent document 1 discloses an ocular optical system formed of a prism having decentering reflective surfaces, and having an arrangement in which, when it is seen from a reverse-light-tracking direction, an observation light entering through a first surface is reflected internally toward the first surface by a second surface, and then is reflected internally from the first surface towards a third surface, thereby being folded into a Z-shaped optical path, and then the observation light forms a real image at the exterior of the prism.
Patent document 2 discloses a prism element having five optical surfaces, wherein observation light entering through a first surface is reflected internally towards the first surface by a second surface, is then reflected internally towards a third surface by the first surface thereby forming an intermediate image within the prism element, is then reflected internally by the third surface, is then reflected internally by a fourth surface, and is thereafter reflected internally by a fifth surface thereby forming an image surface. That is, a prism element is disclosed which relays an intermediate image through the optical surfaces after the third surface.
In addition, an arrangement having four optical surfaces in which the third surface also serves as the fifth surface is disclosed.